U.S. Pat. Nos. 3,708,379 and 3,837,981 describe elastomeric tape and epoxy tape, respectively. The epoxy tape of the latter patent is marketed commercially as an adhesive sealant for a wide variety of applications. The commercial from of epoxy tape has a band of uncured epoxy ribbon which is brilliant deep blue in close side-by-side relation with a band of a curing composition which is yellow.
When portions of the epoxy resin band and curing composition band are mixed prior to application, the striking contrast in color between the bands serves as a mixing indicator, denoting complete mixing of the two components when a uniform color is obtained. In the commercial embodiment, mixing of the epoxy resin component, and curing agent component produces a green mixture which cures to form a green epoxy adhesive sealant. The green color of the cured epoxy adhesive sealant is acceptable in many applications; however, as might be imagined, there are environments where a green adhesive sealant is not acceptable from an esthetic point of view. Of course, other pigments can be used in the respective components of the epoxy tape composition with resultant adhesive sealants having colors other than green, the only requirement being that there be sufficient color contrast between the two components prior to mixing so that it is easy to determine when uniform mixing of the epoxy resin and curing composition has occurred.
A need exists for an epoxy adhesive sealant having all the beneficial attributes of the product described in U.S. Pat. Nos. 3,708,379 and 3,837,981, and which cures to form an adhesive-sealant which is colorless or white. Those in the art will appreciate that a white pigment such as titanium dioxide could be included in the epoxy resin composition and/or the curing agent composition described in U.S. Pat. No. 3,837,981 in a quantity sufficient to render each component white. However, there would be very little, if any, contrast in color between the respective bands, and hence minimal color change would occur on mixing of the two components. Thus, there would be no sharp indication that the components had been sufficiently mixed so as to provide a curable epoxy adhesive sealant, and such a product would be unsatisfactory for this reason.
The object of this invention is to provide an epoxy adhesive sealant which will cure to form an essentially colorless epoxy adhesive sealant. A further object is to provide an uncured epoxy adhesive sealant in which there is contrast in color between the epoxy resin composition and the curing composition which is obtained by including a coloring agent in one of the compositions, a coloring agent which will serve as an indicator that the components have been properly mixed so as to provide a curable epoxy adhesive system, and yet provide an ultimate epoxy adhesive sealant which is essentially colorless or white in its cured state.